745 WTPZ42 KNHC 042034 TCDEP2 Tropical Storm Lorena Discussion Number 12 NWS National Hurricane Center Miami FL EP122025 200 PM MST Thu Sep 04 2025 Strong southwesterly wind shear and cold water temperatures have taken their toll on Lorena. The convection has completely fallen apart and detached itself from the low-level circulation today, leaving an exposed swirl that is evident on GOES-18 visible channels. An Air Force Reserve Reconnaissance Aircraft, which was just in the center, measured maximum 850-mb flight-level winds of 52 kt, which corresponds to about 42 kt at the surface. The central pressure is estimated at 996 mb based on dropsonde data from the aircraft. Additionally, a recent ASCAT pass showed an area of 35-40 kt winds, mostly in the NW quadrant. The initial intensity estimate, based on the aforementioned data, has been reduced to 45 kt. Confidence is high that the cyclone will continue to weaken as it moves over progressively colder water and into stronger southwesterly wind shear. The timing of when Lorena is forecast to weaken to a remnant low has been moved up to 24 h, but it could occur sooner, as most of the convection has already been sheared off well to the northeast of the low-level circulation. The latest NHC track forecast has been shifted slightly to the left, or slightly farther offshore of the Baja California peninsula, compared to the previous NHC forecast, closer to the latest models. Some large rainfall totals have already been observed across portions of Baja California Sur, and the risk of life-threatening flash flooding will continue across portions of the area through Friday. Abundant moisture will continue to stream northeastward away from the cyclone. Because of that, there is still a significant risk of heavy rainfall and flash flooding across portions of Baja California Sur, Sonora, southern Arizona and New Mexico. Key Messages: 1. Heavy rainfall associated with Lorena will continue to impact Baja California Sur and Sonora Mexico through Friday. This will increase the risk of life-threatening flash floods and mudslides across northwest Mexico. 2. Moisture from Lorena will contribute to heavy rainfall concerns across Arizona and New Mexico through Saturday. Isolated to scattered instances of flash flooding are possible across Arizona into Saturday. 3. Life-threatening surf and rip current conditions will affect portions of the southern and western coasts of Baja California Sur during the next couple of days. FORECAST POSITIONS AND MAX WINDS INIT 04/2100Z 24.6N 114.8W 45 KT 50 MPH 12H 05/0600Z 25.0N 114.9W 35 KT 40 MPH 24H 05/1800Z 25.4N 114.8W 30 KT 35 MPH...POST-TROP/REMNT LOW 36H 06/0600Z 25.9N 114.7W 25 KT 30 MPH...POST-TROP/REMNT LOW 48H 06/1800Z 26.3N 114.9W 20 KT 25 MPH...POST-TROP/REMNT LOW 60H 07/0600Z 26.7N 115.3W 15 KT 15 MPH...POST-TROP/REMNT LOW 72H 07/1800Z...DISSIPATED $$ Forecaster Hagen
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